'\" et
.TH REMQUO "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
remquo,
remquof,
remquol
\(em remainder functions
.SH SYNOPSIS
.LP
.nf
#include <math.h>
.P
double remquo(double \fIx\fP, double \fIy\fP, int *\fIquo\fP);
float remquof(float \fIx\fP, float \fIy\fP, int *\fIquo\fP);
long double remquol(long double \fIx\fP, long double \fIy\fP, int *\fIquo\fP);
.fi
.SH DESCRIPTION
The functionality described on this reference page is aligned with the
ISO\ C standard. Any conflict between the requirements described here and the
ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard.
.P
The
\fIremquo\fR(),
\fIremquof\fR(),
and
\fIremquol\fR()
functions shall compute the same remainder as the
\fIremainder\fR(),
\fIremainderf\fR(),
and
\fIremainderl\fR()
functions, respectively. In the object pointed to by
.IR quo ,
they store a value whose sign is the sign of
.IR x /\c
.IR y
and whose magnitude is congruent modulo 2\fI\s-3\un\d\s+3\fR to the
magnitude of the integral quotient of
.IR x /\c
.IR y ,
where
.IR n
is an implementation-defined integer greater than or equal to 3. If
.IR y
is zero, the value stored in the object pointed to by
.IR quo
is unspecified.
.P
An application wishing to check for error situations should set
.IR errno
to zero and call
.IR feclearexcept (FE_ALL_EXCEPT)
before calling these functions. On return, if
.IR errno
is non-zero or \fIfetestexcept\fR(FE_INVALID | FE_DIVBYZERO |
FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.
.SH "RETURN VALUE"
These functions shall return
.IR x
REM
.IR y .
.P
On systems that do not support the IEC 60559 Floating-Point option, if
.IR y
is zero, it is implementation-defined whether a domain error occurs or
zero is returned.
.P
If
.IR x
or
.IR y
is NaN, a NaN shall be returned.
.P
If
.IR x
is \(+-Inf or
.IR y
is zero and the other argument is non-NaN, a domain error shall occur,
and a NaN shall be returned.
.SH ERRORS
These functions shall fail if:
.IP "Domain\ Error" 12
The
.IR x
argument is \(+-Inf, or the
.IR y
argument is \(+-0 and the other argument is non-NaN.
.RS 12 
.P
If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is
non-zero, then
.IR errno
shall be set to
.BR [EDOM] .
If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is
non-zero, then the invalid floating-point exception shall be raised.
.RE
.P
These functions may fail if:
.IP "Domain\ Error" 12
The
.IR y
argument is zero.
.RS 12 
.P
If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is
non-zero, then
.IR errno
shall be set to
.BR [EDOM] .
If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is
non-zero, then the invalid floating-point exception shall be raised.
.RE
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
On error, the expressions (\fImath_errhandling\fR & MATH_ERRNO) and
(\fImath_errhandling\fR & MATH_ERREXCEPT) are independent of each
other, but at least one of them must be non-zero.
.SH RATIONALE
These functions are intended for implementing argument reductions which
can exploit a few low-order bits of the quotient. Note that
.IR x
may be so large in magnitude relative to
.IR y
that an exact representation of the quotient is not practical.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIfeclearexcept\fR\^(\|)",
.IR "\fIfetestexcept\fR\^(\|)",
.IR "\fIremainder\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "Section 4.20" ", " "Treatment of Error Conditions for Mathematical Functions",
.IR "\fB<math.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
